Metallizing spray gun



March 6, 1951 G. DUCClNl ET AL METALLIZING SPRAY GUN 2 Sheets-Sheet 1 Filed Nov. 25, 1944 INVENTORS GAETANO DUCC/Nl.

PR/MO R. CAREDIO.

A TTORNEK March 6, 1951 DUCCIN] EI-AL 2,544,259

METALLIZING SPRAY GUN Filed Nov. 25, 1944 2 Sheets-Sheet 2 O Ill/II v/ W INVENTORS, GAETA/VO DUCC/Nl. Y PR/MO R. CARED/O.

MJWQ/ A T TORNE K Patented 1951 METALLIZIN G SPRAY GUN Gaetano Duccini and Primo R. Carerlio, San Francisco, Calif.

Application November 25, 1944, Serial No. 565,077

This invention relates to spray guns and particularly to a device for flame-spraying pulverulent material onto a surface sought to be coated, whereby said material is melted and fused on said surface.

The invention relates particularly to a method and apparatus for producing vitreous and metallic coatings in a manner similar to that taught in our prior Patent 2,058,218, issued October 20, 1936. The spray gun provided by the present invention is particularly adapted for use with the apparatus disclosed in our co-pending application, Serial Number 469,898, now Patent 2,427,- 448, issued September 16, 1947. Though the spray gun provided by the present invention is intended primarily for use in producing coatings by flame spraying pulverulent fusible materials, it will be understood by those skilled in the art that the novel features of the gun are useful in other types of spray guns.

Objects of the invention are to provide a spray gun capable of variable control of a plurality of fluids conveyed thereto from different sources; to provide a device for producing vitreous or metallic surfaces adapted to be used in conjunction with pulverulent materials having varying characteristics of melting point and specific density and whereby the application of said coating materials is not limited by the velocity thereof during mixing with combustible gases or conveyance to said gun; to provide a device for producing vitreous and metallic surfaces adapted to apply a fusible pulverulent to a surface sought to be coated and simultaneously preheat said surface; to provide a spray gun for producing vitreous or metallic surfaces adapted to anneal deposit areas concurrently with the deposit operation and the preheating of uncoated areas of the work surface; to provide a spray gun for producing vitreous or metallic surfaces wherein combustible gases and pulverulent material are thoroughly mixed; to provide a gun for producing vitreous or metallic surfaces, wherein the manner .of pulverulent emission therefrom may be varied according to circumstances and condition; to provide a gun for producing vitreous and metallic surfaces wherein the velocity of emission of the pulverulent-carrying gases may be varied and controlled within the confines of the said gun; to provide a gun having a pilot flame adapted to aid in the heating of the pulverulent materials and preheat the surface to be coated concurrently with the deposit of material thereon, thereby speeding up the application process and rendering the operation more efficient and economical; to provide a gun 13 Claims. (Cl. 91-122) for producing vitreous or metallic surfaces which has no tendency to backfire or develop a back pressure during use or when the feed of combustible gases thereto is stopped; to provide a gun wherein there is no tendency of the fusible pulverulent to coagulate at the point of discharge or prior to adherence to the surface to be coated; to provide a spray gun wherein a constant pilot flame may be controlled before, after, and during the deposit of pulverulent materials: and to' provide a gun wherein the flame may be adjustably regulated prior to the emission of pulverulent material therefrom.

Other objects and advantages will become apparent upon reference to the accompanying specification.

In the drawings. similar characters of reference represent corresponding parts in the several views.

Fig. 1 is a longitudinal axial sectional view of the spray gun.

Fig. 2 is a transverse sectional view, taken on line 2--2 of Fig. 1.

Fig. 3 is a transverse sectional view, taken on line 3-3 of Fig. 1.

Fig. 4 is a schematic view showing how the deposit flame and p lot flames are believed to react on the work surface.

Fig. 5 is a schematic view of the tip end of the gun wherein the tip discharge orifice is circular.

Fig. 6 is a schematic view of the pilot flames and depo it flame as produced by the tip of Fig. 5.

Fig. '7 is a schematic view of the deposit and preheating area produced by the tip of Fig. 5.

Fig. 8 is similar to Fig. 5 except the tip discharge orifice is rectangular.

Fig. 9 is a schematic view of the pilot flames and deposit flame as produced by the tip of Fig. 8.

Fig. 10 is a schematic view of the deposit and preheating area produced by the tip of Fig. 8.

Fig. 11 is a schematic view showing a plurality of deposit areas produced by the tip of Fig. 8.

Fig. 12 is a longitudinal sectional view of the plurality of deposits of Fig. 11.

Fig. 13 is a longitudinal sectional view of a modified form of tip.

The spray gun is preferably in the form of a pistol, having a barrel portion, generally indicated at 2, and a handlegrip portion, generally indicated at 3. The barrel portion comprises a plurality of tubular members spaced concentrically from one another to form a plurality of annular fluid passages.

For purposes of description, we will refer to a hollow base member, generally indicated at 8. to

which is threaded an outer tubular shell extend- *site end of hollow base member 5 to form the butt" portion 9 of the gun barrel. The butt portion is spaced from the base member to form an annular chamber l0 which communicates with a centrally located mixing and distributing chamber H. A centrally perforated plug I2 is threadably inserted in threaded bore l3, provided in the end of butt portion 9. The plug is rigged exteriorly as at H, for connection to a conduit leading from an appropriate supply source.

A tubular insert is threadably engaged to an annular shoulder i6 of base member 5 and is spaced concentrically from shell 6. A threaded washer or ring I1 is connected to the tubular extension l8 of base member 5 and fits snugly against the inner surface of shell 6 to form the tip end face of the gun. The ring I1 is provided with two sets of perforations i9, spaced concentrically of one another, said perforations bein forwardly directed as shown and opening into chamber 20. The washer or ring II abuts against the end of insert l5, and extends transversely of the gun to constitute a forward closure member for chamber 20. The insert i5 is provided with a plurality of perforations 2| adjacent to the shoulder iii. The space between outer shell 6 and tubular extension portion l8, partitioned by perforated insert l5, forms the distributing chamber for gases conveyed thereinto by the plurality of passages 22 bored through'base member 5 and communicating with annular chamber It). It will be seen in Fig. 1 that, when combustible gas under pressure is supplied to chamber ll, some of the gas will be conveyed from that chamber by passage l0 and thence forwardly through passages 22 into chamber 20 to supply the forwardly directed perforations I9. Since, as hereinafter described, ignition of the gas escaping forwardly through perforations i9 establishes a tubular pilot flame for shrouding the spray discharge of thegun, we refers to perforations i9 as pilot apertures.

A mediate tubular insert 25 is provided interiorly of extension portion I 8 and is flared outwardly at one end, as at 26, for threaded connection with the inner annular wall of hollow base member 5. The insert 25 effects a direct communication with distributing chamber II. The mediate insert 25 is concentrically spaced from extension iii to form an auxiliary annular fluid passage 21 communicating with an annular distributing chamber 28, defined by the recessed inner wall 29 of base member 5 and the outer wall oi mediate insert 25. The forward or tip end of mediate insert 25 is provided with an annular raised portion provided with a plurality of grooves 30, tapered upwardly toward the tip end. The ridges of the grooves are tapered to nest against the inner annular, hollow, conical wall of the tip 8. The grooves allow gas to be emitted from the auxiliary passage 21 into hollow tip 8 in the form of spaced streams or jets, to be there thoroughly mixed with the other gases there converging, as will shortly appear. The grooves 30 also act as restricted discharge orifices to increase or decrease the velocity of gas discharge by rotation of the tip, if desired.

In this connection it is noted that if the tip is screwed 0r unscrewed on tubular extension portion it to which it is threadably connected, it

4 moves longitudinally relative to mediate insert 2! and hence the volume and velocity of gases emitted through the grooves 3| or between ,the inner wall of tip 8 and the tapered discharge grooved end of mediate insert 25 maybe controlled. I

A central, tubular, perforated insert 85 is threadably connected into plug i2 and extends coaxially of mediate insert 25 to terminate short of the tip end thereof and is spaced concentrically therefrom to form a central, annular passage having direct access to mixing and distributing chamber H. The ,central insert is provided with a plurality of pairs of diametrically opposed apertures 31 and 38. The pairs of apertures 31 and 38 are staggered so that the axis of each pair is approximately ninety degrees opposed tothe axis of an adjacent pair. The first pair of apertures 31 is spaced forwardly of the chamber I l a sufficient distance, preferably about a quarter of the distance from said chamber to the tip end of the perforated, central insert, to prevent any of the material carried in said insert from entering into annular chamber Ill.

The hollow, conical tip 8, having a discharge orifice 40, is adapted to be removably connected to the threaded tip end of extension l8, as herein illustrated. The hollow interior of tip 8 forms a mixing and collecting chamber H where gases emitted from passages 21 and 36 and insert 35 converge for cumulative discharge through discharge orifice 40, spaced outwardly from said passages and insert and enclosing the same. The discharge aperture is illustrated in Fig. 3 as being circular in cross section, but tips having varying shapes and sizes of discharge apertures may be interchangeably used for the purposes heerinafter mentioned.

In Fig. 13 we have illustrated a modified form of a tip, generally indicated at 43. The tip comprises a hollow body provided with threads 44 for connection to the threaded tip end of tubular extension portion 18. The inner, annular wall of the tip is adapted to nest against the tapered grooved end of the mediate insert 25 in the same manner as tip 8. above described. A central discharge orifice 45 is provided in the tip and is flared outwardly. as at 46.

We have provided a projecting annular offset 41 ad acent to the discharge orifice. The gases conveyed into the tip from the various fluid passages are emitted from tip 43 in such a manner that the coating material is projected against the work surface in an efllcient manner, enabling fast application of the coating. The inner annular oflset 4'! creates a discharge curent not heretofore obtainable and which is highly desirable in producing certain vitreous or metallic surfaces in that the discharge current is spread over a greater area.

The passage provided in the plug l2 leading to central insert 35 is connected toa source of mixed gas, air and pulverulent material, such as powdered glass or metal, as described in our said Letters Patent Nd. 2,058,218, issued October 20, 1936, and our Letters Patent No. 2,427,448, issued September 16, 1947. This mixture, for convenience, will be referred to as the material, although, in practice, the material is conveyed to the gun, under pressure, in suspension by air and combustible gas.

The chamber II is connected to a suitable source of combustible gas and air under pressure through conduit 50 in handle 3. The gas and air mixture will be referred to as the operating gases, for convenience.

The chamber 28 is connected, by conduit 5|, leading through handle 3, to a suitable supply of mixed gases, under pressure, such as oxygen and butane. The gaseous mixture leading to chamber 28 will be referred to as the control gases, for convenience.

The fluent spray material is supplied to the interior of tube 35 from an exterior source under pressure, and chambers H and 28 are supplied with gas from separate exterior sources under pressure. As shown in Patent 2,427,448, the supply lines connected to spray guns of the type here described are controlled by suitable manually operated valves.

It will be clear, upon reference to Fig. 1, that some of the operating gases have access from the chamber ii to annular chamber ID, from whence they are conveyed, through passages 22, to partitioned annular mixing and distributing chamber 20 for dispersal through pilot perforations IS in the form of circular, concentric flames, when ignited. The remainder of the operating gases is discharged into central passage 36 to commingle with the material carried in perforated insert 35, as will be described shortly.

The control gas is conveyed from a suitable exterior supply line through conduit 5!, chamber 28 and auxiliary passage 21 to tip 8. The spray material, supplied under pressure by an exterior supply line connected to member l2, flows to the interior of tube 35. The combustible operating gas is conveyed from a suitable exterior supply line through conduit 50 and chamber ll into the passage 36 between tube 35 and imperforate tubular member 25, some of the gas from chamber H of course being supplied forwardly to pilot apertures i9 as previously described.

The combination of tube 35, including perforations 31, 38, and imperforate tubular member 25 functions as means for mixing the spray material and operating gas and directing the mixture forwardly through tip 8. It will be obvious to those skilled in the art that, depending upon the relative velocities of the spray material within tube 35 and the operating gas in passage 36, there will be a flow through perforations 31, 38, either a flow of operating gas inwardly to the interior of tube 35, or a flow of spray material outwardly into passage 36. The relative velocities of the spray material in tube 35 and the operating gas in passage 36 of course depend directly upon the relative pressures in the exterior supply lines to which the gun is connected.

We prefer to connect the tube 35 to a source of spray material which is at a relatively greater pressure than is the operating gas supplied to passage 36, and thus to obtain a relatively high velocity of spray material in tube 35 and a relatively lower velocity of operating gas in passage 33. Since the velocity of the operating gas in passage 36 is lower than that of the spray material in tube 35, the pressure within tube 35 will be lower than the pressure in passage 36, and operating gas will therefore pass inwardly through perforations 31, 38 to the interior of tube 35, there commingling with the spray material.

Since many of the pulverulent materials which the gun is intended to spray have relatively high densities, the velocity of the spray material must necessarily be relatively high. Use of the combination of perforated tube 35 and imperforate tubular member 25 as shown in the drawings achieves the mixture of operating gas with the high velocity stream of spray material, a function heretofore diflicult to attain.

As seen in Fig. 1. the tube 35 terminates short of the discharge end of imperforate tubular member 25, the latter extending forwardly and being closely spaced from the tapered inner wall of tip 8. Thus, the mixture of spray material and operating gas produced within tube 35 as hereinbefore described enters, along with the-operating gas not aspirated through perforations 31 and 38. into the chamber 4i prior to discharge through orifice 40.

The control gases not only enable regulation of discharge velocity but also the flame temperature. This is an important factor as some coating materials have higher melting and fusing points than other materials. Consequently, if a material tobe sprayed is characterized by a high melting point a mixture of oxygen and butane or other highly combustible material is used as control gases, the velocity of which may be determined by tip adjustment according to the specific density of the said material. On the other hand, if a low melting point material is employed, the control gases may essentially comprise an air mixture impinged thereon at a relatively high velocity.

By means of the pilot flames, established by ignition of the gas discharged through the two sets of pilot apertures IS, the operator is insured of a constant ignition flame which performs the added function of preheating the work surface concurrently with the deposit of material as well as the post-deposit annealing function.

Fig. 4 shows a schematic view of the manner in which the deposit flame A-and pilot flames B are believed to react on the work surface C. As the deposit flame sprays material on the surface C for fusion, the concentric pilot flames heat the work surface adjacent to the deposit area to insure a greater'bond. Formerly, the preheating of the surface to be coated was a separate timeconsuming operation.

Figs. 11 and 12 show deposit areas F and the pilot flames 13 having a post-deposit function of annealing the area already coated concurrently with the deposit operation and the preheating of uncoated surfaces.

Fig. 5 shows schematically a gun head equipped with a tip having a circular discharge aperture. The circular discharge orifice is particularly useful in spraying small or oddly shaped work surfaces.

Figs. 6 and 7 show the pilot flame areas D and deposit area E.

Fig. 8 shows schematically a gun head equipped with a tip 8a having a rectangular discharge orifice 40a which is especially adapted for use in coating flat work surfaces.

Figs. 9 and 10 show the pilot flame areas D and deposit area E. The shape of the deposit is roughly represented at F in Fig. 10.

Figs. 11 and 12 show roughly how the deposits are overlapped to form a continuous smooth surface coating. v

Our invention is useful in producing vitreous or metallic surfaces and has been described with particularity in that regard. However, it is pointed out that the gun has many uses other than as especially illustrated and described, and the claims are not intended to be limited to a use of the invention.

The gun has been described in detail of structure for purpose of clarity and illustration. It is understood that modifications and variations of the gun structure, assembly, and use are not limited except by the spirit of the invention and appended claims.

We claim:

1. In a spray gun of the type described, a pair of imperforate tubular members arranged longitudinally of the gun and spaced substantially coaxially to provide an outer auxiliary passage and a central passage; a tube disposed concentrically within said central passage and terminating in a discharge end short of the forward ends of said passages, said tube being provided with a plurality of openings spaced along the tube and allowing free communication between the interior of said tube and said central passage; means whereby the interior of said tube may be connected to an exterior source of fluent spray material under pressure; means whereby a combustible operating gas under pressure from an exterior supply may be conducted to said central passage around said tube; means whereby a combustible control gas under pressure may be conducted to said auxiliary passage, and a longitudinally adjustable hollow tip having a discharge orifice and being arranged to receive fluid discharged from said passages and said tube, the interior wall of said hollow tip encompassing the forward ends of said passages.

2. In a spray gun, a pair of imperforate tubular members arranged longitudinally of the gun and spaced substantially coaxially to provide an outer auxiliary passage and a central passage; a hollow tip carried by the outer member of said pair of tubular members at the forward end thereof' and arranged for longitudinal adjustment thereon, said hollow tip tapering forwardly and terminating in a discharge orifice smaller than the cross-sectional area of said central passage; a tube disposed coaxially within said central passage and terminating short of the forward end thereof, said tube being provided with a plurality of longitudinally spaced perforations, said auxiliary passage communicating with a first gas inlet, said central passage communicating with a second gas inlet, and said tube being arranged for connection to an exterior supply line for fluent spray material.

3. In a spray gun of the type described, a hollow tip tapering forwardly and terminating in a discharge orifice, means for mixing fluid-entrained pulverulent spray material with a combustible gas and directing the mixture forwardly through said tip, a member extending transversely of the gun behind said discharge orifice and including a plurality of forwardly directed pilot apertures arranged outwardly of said tip, and means for conducting combustible gas forwardly to said pilot apertures.

4. In a spray gun of the type described, a hollow tip having a discharge orifice, means for mixing fluent spray material and combustible gas and directing the mixture forwardly through said tip, a disc-like member arranged transversely of the gun at said tip and including a series of forwardly directed pilot apertures spaced concentrically outward of said tip, and means whereby combustible gas may be directed forwardly through said pilot apertures.

5. In a spray gun of the type described, a tubular outer shell; an imperforate tubular member arranged coaxially within said shell; a hollow disclosure tip carried by said tubular member at the forward end thereof; means within said tubular member for mixing combustible gas and fluentspray material and directing the mixture through said hollow tip; an annular member arranged in a plane transverse to the gun at said tip and positioned to close the space between said shell and said tube, said member being provided with a series of forwardly directed pilot apertures arranged concentrically outward of said tip, and means for conducting combustible gas from an exterior supply line to the space between said shell and said tip behind said annular member.

6. In a spray gun of the type described, a base member carrying a forwardly directed imperiorate tube and a tubular shell arranged substantially concentrically outward of said tube; a hollow tip carried by said tube at the forward end thereof and provided with a discharge orifice; means within said tube for mixing combustible gas and spray material and directing the mixture forwardly through said tip; an annular member carried by said tube adjacent said tip and extending transversely of the tube to provide a forward closure for the space between said shell and said tube, said member being provided with a series of forwardly directed pilot apertures arranged concentrically outward of said tip, and means whereby combustible gas under pressure from an exterior source may be conducted to the space between said tube and said shell to supply said apertures.

7. A spray gun of the type described having an auxiliary annular passage provided with a gas inlet and terminating in a discharge end forward of the gun; a central passage provided with a separate gas inlet and terminating in a discharge end forward of said gun; a tube disposed within said central passage and extending through the gas inlet thereof, said tube being arranged for connection to an exterior fluid supply line and being provided along a portion of its length within said central passage with a plurality of spaced perforations; a longitudinally adjustable hollow tip having a discharge orifice, the interior wall of said tip being spaced from the discharge ends of said auxiliary and central passages to form a mixing chamber; a member extending transversely of the gun at said tip, said member being provided with a plurality of forwardly directed pilot apertures arranged concentrically outward of said tip, and means whereby combustible gas may be directed forwardly through said pilot apertures.

8. In a spray gun of the type described, a series of tubular members spaced substantially coaxially to define an outer annular passage, an intermediate auxiliary passage, and a central passage; a tube disposed within said central passage and provided with a plurality of longitudinally spaced perforations; a hollow tip having a discharge orifice, the interior of said hollow tip communicating with said auxiliary passage, said central passage and the interior of said tube, and a transversely extending member located at said tip and closing said outer annular passage, said transversely extending member being provided with a plurality of forwardly directed pilot apertures communicating with said outer annular passage and arranged concentrically outward of said tip, said tube being arranged for connection to a source of spray material under pressure, said central and outer passages communicating with a single gas supply inlet, and said auxiliary passage communicating with a separate gas supply inlet.

9. In a spray gun of the type described, an imperforate tubular member carrying a hollow tip at the forward end thereof. said tip includwardly to said pilot apertures, said apertures being spaced sufliciently closely to each other that when combustible gas supplied under pressure through said pilot apertures is ignited, a substantially continuous tubular flame is produced to surround the discharge spray from said tip.

10. In a spray gun of the type described, a base member carrying a forwardly directed imperforate tubular member-and a hollow 'shell spaced outwardly of said tubular member; a hollow tip having a discharge orifice and being arranged to control emission of fluid from the forward end of said tubular member; means disposed within said tubular member for mixing spray material and combustible gas and directing the mixture forwardly through said tip; a transversely extending member disposed adjacent to said tip at the rear thereof, said transversely extending member closing the space between said tubular member and said shell and being provided with a series of forwardly directed, circumferentially spaced pilot apertures disposed concentrically outward from said tip and opening into the space between said tubular member and said shell, and means for conducting combustible gas under pressure from an exterior source to the space between'said tubular member and said shell to supply said pilot apertures, the circumferential spacing of said pilot apertures being such that ignition of gas supplied through said apertures establishes a continuous tubular pilot flame surrounding said tip and the spray discharge therefrom.

11. In a spray gun of the class described, the

combination of an imperforate tubular member.

having an outlet end forwardly of the gun; a tube arranged concentrically within said tubular member, said tube being provided with a plurality of longitudinally spaced perforations; a hollow tip having a discharge orifice and being arranged to control the total flow of fluid emitted from said tubular member and said tube; means whereby the interior of said tube may be connected to an exterior supply of fluent spray material under pressure, and means whereby gas under pressure from an exterior supply may be conveyed to the space between said imperforate tubular member and said tube.

12. In a spray gun of the class described. the combination of an imperforate tubular member having an outlet end forwardly of the gun; a tube disposed concentrically within said imperforate tubular member and terminating short of the outlet end thereof, said tube being provided with a plurality of longitudinally spaced perforations; a tapered hollow tip terminating in a discharge orifice smaller than the crosssection of the space enclosed by said imperforate tubular member, said tipbeing positioned to receive the total flow of fluid from said imperforate tubular member and said tube; means whereby said tube may be connected to an exterior supply line for carrying fluent spray material under pressure, and means whereby gas under pressure from an exterior supply line may be conveyed to the space between said imperforatetubular member and said tube.

13. In a spray gun of the type described, an imperforate tubular member having a discharge end forwardly of the gun; a hollow tapered tip positioned to receive and control the total fluid emitted through the discharge end of said imperforate tubular member, said tip terminating in a discharge oriflce smaller than the crosssection of the space enclosed by said'imperforatetubular member; a tube mounted concentrically within said imperforate tubular member and provided with a series of longitudinally spaced perforations, said tube terminating short of the discharge end of said imperforate tubular member; connecting means whereby the interior of said tube may be connected to an exterior supply of fluent spray material under pressure, said connecting means being located at a point substantially removed from the discharge end of said imperforate tubular member andsaid series of perforations in said tube being situated between said discharge opening and said connecting means; and means whereby gas under pressure may be conveyed to the space between said imperforate tubular member and said tube.

GAETANO DUCCINI. PRIMO R. CAREDIO.

REFERENCES CITED 7 The following references are of record in the flle of-this patent:

. UNITED STATES PATENTS Number Name Date 1,617,166 Schoop Feb. 8, 1927 1,897,683 Tracy Feb. 14, 1933 1,930,373 Stubenr'auch Oct. 10, 1933 2,091,021 Stevens Au 24. 1937 2,125,445 Holveck Aug. 2, 1930 2,427,448 Duccinieta1 Sept. 16, 1947 2,436,335 Simonsen Feb. 17,1943 

